This application is a 371 of PCT/JP99/04262 filed Aug. 6, 1999.
The present invention relates to a method for easily producing glycopeptides which will be useful for scientific studies, medicaments and foodstuffs, as well as a method for the production of polymers thereof. More particularly, it relates to a novel method for producing stereoselective glycopeptide monomers, their polycondensation products:sequential glycopeptides.
Recently, many new findings have been reported as to the role of glycosylation within biobody, and research technology in glycosylation biology, glycosylation engineering and the like have widely been applied to the fields of medicament, foodstuffs. Particularly, it has been found that complex glycosides, especially glycoproteins, glycopeptides wherein glycosylation chains bond to proteins, participate deeply in cellular recognition, differentiation, fertilization, senescence, canceration, or the like within biobody. Under the circumstance, many researchers have tried to synthesize glycosylation chain having natural structure or new glycosylation products. However, glycosylation has a plenty of branch points and has also various forms in binding of monosaccharides in each unit thereof. Accordingly, it is very difficult to obtain glycosylations or glycopeptides which have highly controlled structure.
In the conventional method for producing glycopeptides by using a fluorinated glycoside having an acyl-type protecting group as a glycoside donor and coupling it with a peptide (Tsuda et al., Chem. Comm. 2279 (1996)), there is a possibility of occurrence of cleavage of glycosylation or racemization of the peptides.
The known methods for synthesis of glycopeptides are all carried out by extending sequentially the chains of amino acids, for example, a method for extending peptide chains using a solid phase (Nakahara et al., Carbohydr. Res., 292, 71-81 (1996)) or a method for extending the peptide chain in a liquid phase (Kuntz et al., Ang. Chem. Int. Ed. Engl., 36, 618-621 (1997). The sequential chain extending method is disadvantageous in that the procedure for protection and deprotection shall be repeated in multiple steps. Moreover, it has a defect in that the multiple step reaction requires also multiple purification procedures and also results in much loss of the materials.
An object of the present invention is to provide a method for producing glycopeptides by a very simple procedure. Another object of the invention is to provide a method for producing sequential glycopeptides by polycondensing a glycopeptide monomer.
The present inventors have found that the desired glycopeptides can easily be produced by using a fluorinated glycoside of a monosaccharide or an oligosaccharide wherein the hydroxy groups are protected by an ether-type protecting group and coupling the fluorinated glycoside with an amino acid or a peptide derivative and thereafter deprotecting the glycopeptides by hydrogenation at one time, and further that sequential glycopeptides can easily be obtained by subjecting the glycopeptide thus obtained to polycondensation in the presence of a peptide condensing agent, and then have accomplished the present invention.